What diversification is

Diversification is spreading capital across different assets so a bad event in one place doesn't sink everything. The familiar idea is not putting all your eggs in one basket. But real diversification must consider correlation, not just count assets.

Why it matters

Proper diversification reduces overall risk without necessarily reducing expected return by the same proportion, so it's seen as one of the rare ways to improve the risk-return relationship. But wrong diversification, only increasing the number of assets while they move together, creates a false sense of safety.

How to apply it

Consider the correlation among portfolio assets: if they tend to rise and fall together, holding many tickers doesn't reduce risk much. Effective diversification finds assets that don't move alike, so when one part falls the other doesn't fall at the same time. Also avoid the opposite extreme of spreading so thin that it's unmanageable and dilutes even good positions.

A concrete example

Someone holds ten stocks and believes they're diversified, but all ten belong to one sector moving together. When that sector hits bad news, all ten fall, and the portfolio behaves as if it held one asset. Conversely, holding fewer assets that are less correlated can reduce risk better. Quantity doesn't substitute for correlation difference.

Common mistakes

  • Counting the number of assets rather than considering their correlation.
  • Creating false safety by holding many tickers in the same sector.
  • Spreading so thin it's unmanageable and dilutes good positions.
  • Forgetting correlation can rise exactly during a crisis, when many assets fall together.

FAQ

  • Is holding many tickers already diversification? Not necessarily. If they're highly correlated and move together, you're not truly diversified despite holding many.
  • Does diversification reduce returns? It can smooth results and reduce risk; the tradeoff is not concentrating everything on a single big win.
  • How many assets is enough? No fixed number; what matters is that they're lowly correlated, not high in count.

Checklist

  • ☐ Are my assets lowly correlated with each other?
  • ☐ Am I truly diversifying, or just holding many tickers that move together?
  • ☐ Am I spread so thin it's unmanageable?